X-ray apparatus including counterbalancing mechanism for spot filmer or the like

ABSTRACT

X-ray table and spot filmer arrangement in which two to one mechanical advantage is obtained on counterweights to reduce weight requirements and rectilinear parking of the spot filmer is obtained.

United States Patent Norgren [45] Oct. 28, 1975 X-RAY- APPARATUSINCLUDING COUNTERBALANCING MECHANISM FOR [56] References Cited SPOTFILMER OR THE LIKE UNITED STATES TS [75] Inventor: Edwin A. Norgren,Cleveland 2,552,858 5/1951 Mueller 250/445 Heights, Ohio 2,659,01011/1953 Hardenberg 250/445 2,890,346 6 1959 K 250/471 [73] Asslgnee 2;?"Cleveland, 3,325,643 6/1967 C22 250/444 [22] Filed; Se t, 23, 1974Primary Examiner-Craig E. Church Attorney, Agent, or Firm-Watts,Hoffmann, Fisher & ,[21] App]. No.. 508,176 Heinke Related US.Application Data [63] Continuation of Set. N0. 656,448, July 27, 1967,ABSTRACT abandmed- X-ray table and spot filmer arrangement in which twoto one mechanical advantage is obtained on counter- US. to reducerequirements and rectilinear [5 Clparking of the spot filmer is obtained[58] Field of Search 250/439, 444, 445, 446,

31 Claims, 10 Drawing Figures US. Patent Oct. 28, 1975 Sheet10f43,916,203

INVENTOR.

EDWIN A.NORGREN mi W ATTORNEY.

U.S'. Patent 'Oct.28, 1975 Sheet3of4 3,916,203

FIG.5

INVENTOR. EDWIN A.NORGREN m, m, M 2 14/ ATTORNEYS.

FIG.

X-RAY APPARATUS INCLUDING COUNTERBALANCING MECHANISM FOR SPOT FILMER ORTHE LIKE This is a continuation, of application Ser. No. 656,448, filedJuly 27, 1967, now abandoned.

CROSS REFERENCED'APPLICATIONS AND PATENTS 1. Barrett et al., US. Pat.No. 3,173,008, issued Mar. 9, 1965 under the title Spot Filmer. 2. R. C.Schiring et al., US. Pat. No. 2,872,584 issued Feb. 3, 1959 under thetitle X-Ray Apparatus.

3. R. C. Schiring, US. Pat. No. 2,997,585 issued Aug. 22, 1961 under thetitle Combined Image Amplified and Fluoroscopic Screen Above X-Ray Examinar.

tion Table. V

4. Future application entitled Automatic X-Ray Shutter Control by E. A.Norgren.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention isdirected to X-ray apparatus and more particularly to X-ray tables onwhich a spot filmer or the like is mounted. In X-ray examinationmechanisms, it is now wellknown to provide a so-called 9090 X-ray tablein which a table body is tiltable on its pedestal in either direction 90from a position where the table top is horizontal. Thus, the body of thetable may be moved clockwise or counterclockwise from the horizontaluntil its top is vertical or to any position between the two verticalpositions. One such table is that described and claimed in thereferenced Schiring et al. US. Pat. No. 2,872,584.

Other tables with lesser amounts of tilting are also known. Some tables,for example, have a body which a is tiltable in one direction from aposition with the top horizontal to a vertical position and in the otherdirection to a so-called Trandelenburg position wherein the angle of thetable top is approximately 15 with the hor- I izontal.

In many of the described prior tables, a. guide track which parallelsthe table top is provided. A movable column or tower is reciprocablymounted on the track for movement in a path of travel which islongitudinal with respect to the top. The column is also mounted forreciprocal rectilinear movement along a guide path which is transverseto the top and normal to the column travel along the guide track.

The usual column supports and X-ray tube which is positioned beneaththertable top and within the table body. One or more image-producingX-ray responsive devices such as a spot filmer or an imageintensification device are supported by a carriage. The carriage isreciprocally mounted on the column for travel along a rectilinear pathwhich is perpendicular to the table top.

These three rectilinear paths of travel permit the carrier to be movedto any selected position over the table top and to any selected distancefrom the top within the limits of the respective paths of travel.

Since the movement of the carrier relative to the col umn is verticalmovement when the table top is horizontal, counterbalancing weights arecarried in the column to facilitate the vertical movement of thecarrier. Thus, one pound of weight in the carrier will, with aone-to-one mechanical advantage, mean one pound of counterweight andtherefore two pounds of carrier and. column weight.

Since the column is movable in a vertical path when i the table top isin averticalposition, weights to counterbalance the column are providedin the tableThe it tower or column counterbalancing weights must inriedin the table body as well as those in column, it will be seen that forevery pound of weight on the carrier,

threepounds of counterbalancing weightmust be added to the table. i

With such equipment as an image intensification tube and a cameramounted on the carrier in addition toia. spot filmer,counterbalancinghas become afproblemil In many situations, the maximumlimit of counterweight which can be addedtothe table has been met. i Onesolutionfor assisting in this counterbalancing 1 P problem is to provideceiling-mounted counterbalances i which support weight of a spot filmeror other devices mounted in the column, One such ceiling counters weightis described in US. Pat. No." 2,997,585 issued. Aug. 22, 1961 to R. C.Schiringandentitled CQmfs bined Image Amplifier and Fluorosco p icScreen above X-Ray Examination Table.

Another problem that has. existed positioned in a so-called Bucky traywithin the table body is then exposed. In order to conduct studies withI an overhead tube, it isdesirable that the spot filmer be moved awayfrom the patient to. free completely the space above the patient. 2.Prior art One prior arrangement forparking a spotfilmer has been a pivotconnection of it to the vertical column or Q tower so that it maybepivot upwardly to a relatively, out-of the-way position when notin use.While this has i in the past been reasonably suitable with theincreasingly common use of image intensification tubes con-f nected tothe spot filmer and with greaterweight in the I spot filmers, thisbecomes disadvantageous .both because of the weight of the spotfilmer;andthe suppor ted mechanism, and because of the limited amount ofpiv-' oting which can be obtained when an imagetube and camera areassociated equipment such as a cine mounted on the top of the spotfilmer.

There in the past have been proposals for so-called spot filmer parkingwhere the spot filmer is moved rectilinearly rearwardly into its parkingposition. The

problem that has been experienced, however, is that with the amount ofcounterbalancing required in the tower, clearnace which permitsthe spotfilmer to be parked rectilinea'rly has not beenobtainable with thecoutnerweights in the tower. With one system used to overcome thisproblem when reciprocal parking has been provided, the counterweightsforthe imaging de vice and its carriage have been carried in the table anda pulley and cable arrangement has been provided to interconnect thecounterweights and the 'spotfilmer.

Even though there have been a few prior attempts at I providingso-called doubling arrangement to reduce the amount of counterweightrequired, neitherthose proposals nor any other prior artproposal hassuggested an arrangement wherein the counterweights can .in the priorart is, a i that of so-called parking of an imaging devicesu ch as aspot filmer, There are certain procedures where an X-ray tube supportedeither on a bi-rail device or by e a ceiling mount is positioned abovethe patient. A film be positioned in the tower in a system where a spotfilmer or other imaging device can be parked by rectilinear motion overthe top of the tower.

SUMMARY OF THE INVENTION The present invention provides a novelcounterweighting system and parking arrangement for image devices.Typical imaging devices are the spot filmers which have been mentionedand frame structures the size of spot filmers which carry X-raysensitive image intensification tubes. The invention will be describedin conjunction with a spot filmer as exemplary of imaging devices.

With this invention, an intermediate carriage is pro vided; Theintermediate carriage supports, through a pulley arrangement, acounterweight and is connected to a pulley arrangement to which the spotfilmer is connected. As a spot filmer is brought down, the intermediatecarriage rises the same amount. The counterweight carried by thecarriage moves upwardly relative to the carriage the same amount as thespot filmer movement and this, coupled with the intermediate carriagemovement, produces movement of the counterweight twice that of the spotfilmer. With twice the movement and a mechanical advantage attendant toit, approximately one-half the normal weight required forcounterbalancing is utilized.

When the spot filmer is raised to its parked position, the intermediatecarriage and the counterweight are lowered concurrently to storagepositions. The outstanding advantage of reciprocal or rectilinearparking at a convenient height and level is achieved by providing atable column which is open at the top. When the spot filmer is fullylowered, the intermediate carriage and the counterweights carried by itproject upwardly out of the column. When the spot filmer is at its topparked position, the carriage and counterweight are in their storagepositions which are within the column. This permits facile parking ofthe spot filmer above the column at the convenient and relatively lowheight.

Another feature of the invention resides in a novel latching arrangementwhich, among other advantages, positively prevents any vertical spotfilmer movement until the filmer is fully out of its parked position.

Accordingly, the object of this invention is to provide, in an X-raytable equipped with a tower and spot filmer or similar device on it, aparking arrangement which is rectilinear in combination with acounterweighting arrangement which is doubling arrangement to reduce theamount of weight required.

Other objects and a fuller understanding of the invention may be had byreferring to the following description and claims taken in conjunctionwith the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showingfragmentary portions of an X-ray table, a column on the table, and aspot filmer in the parked position achieved with this invention;

FIG. 2 is a rear elevational view of the column, showing in dotted linesthe intermediate carriage and the pulley arrangement;

FIG. 3 is a top plan view of the table column, the intermediate carriageand the counterweighting arrangement;

FIGS. 4 and 5 are sectional views as seen respectively from the planesindicated by the lines 4-4 and 5-5 of FIG. 2;

FIGS. 6 and 7 are diagrammatic views showing the pulley arrangementembodiment within the table column;

FIG. 8 is a sectional view of the carriage for the imaging device usedwith this invention, showing a partially sectioned view of one of theimage device tracks in its parked position, fragmentary views of themast tracks, and a plan view of a latching device;

FIG. 9 is a fragmentary sectional view corresponding to the upperportion of FIG. 10, showing the imaging device track in a transitoryposition between the park and operating positions; and,

FIG. 10 is a view corresponding to FIG. 9 showing the imaging devicetrack in its operating position.

Referring to the drawings and to FIG. 1 in particular, a fragmentaryportion of the table body is shown generally at 10. The table bodyincludes a top 11, which, in the embodiment shown, is movable alongtracks 12. The table body carries a tower shown generally at 14. Thetower 14 includes a horizontal carriage portion 15 which is supported onthe usual tracks within the table body 10 for rectilinear movementparallel to the table top 11. The carriage portion 15 is mounted forreciprocal movement both transverse with respect to the table top andlongitudinal with respect to the table top so that the spot filmer showngenerally at 17 can be positioned at any location over the table top 11.

The tower includes a vertical mast 18 which is equipped with guidetracks 19, 20, 20a on which a support carriage 21 for the spot filmer orother imaging device is mounted. Rollers 16 carried by the spot filmercarriage 21. FIG. 8, permit the spot filmer carriage to moverectilinearly along the tracks 19, 20, 20a in a path toward any awayfrom the table top 11.

The spot filmer 17 has horizontal tracks 22, FIG. 1, which coact withrollers 23, FIG. 8, within the spot filmer carriage 21. These rollerspermit the spot filmer 17 to be shifted rectilinearly along a pathparalleling the table top from the parked position shown in FIG. 1 to aforwardly extended position over the table top. In its forwardlyextended position, the spot filmer is completely forward of the towerand mast portion 18.

The spot filmer 17 may be of the type described in the above-identifiedBarrett et al. patent. It includes a front load opening indicated by thearrow 24 through which a cassette containing film may be inserted andwithdrawn. It also includes the usual shutter controls 25, a switch forturning on magnetic locks 26, an exposure control button 27, apositioning handle 28, and other allied structure which will be readilyrecognized by mechanism skilled in the art.

Referring now to FIGS. 6 and 7, the spot filmer 17 and its carriage areindicated in Phantom lines. The spot filmer carriage is connected at 30to a first or mast endless cable 31. The mast cable 31 is reeved overmast pulleys 32 which are, as will be explained presently, journaled inthe mast 18.

An intermediate carriage 33 is provided. The intermediate carriage 33 isconnected at 34 to mast cable 31. With this construction, as the spotfilmer is lowered from the position shown in FIG. 6 to the positionshown in FIG. 7, the connection at 30 of the spot filmer to the mastcable 31 will shift the cable causing the mast pulley 32 to rotate in aclockwise direction. This action simultaneously causes the connection 34of the intermediate carriage 33 to rise and the intermediate carriage 33to rise from the position of FIG. 6 to that of FIG. 7 in a manner whichwill be described in more detail presently.

The intermediate carriage 33 carries carriage pulleys 35. A second orcarriage endless cable 37 is reeved around the carriage pulleys 35. Thecarriage cable 37 is anchored at 36 to the frame of the mast l8.

A counterweight carriage assembly composed of counterweights and acounterweight carriage is indicated by the numeral 38. The counterweightassembly is mounted by rollers 39 on the intermediate carriage 33 formovement relative to it. The counterweight carriage is connected at 40to the carriage cable 37.

Since the carriage cable 37 is anchored to the frame at 36, movement ofthe intermediate carriage 33 upwardly due to downward movement of thespot filmer 17 will cause the carriage cable 37 to move a distancerelative to the carriage equal to the amount of movement of the mastcable 31. Expressed another way, the

amount as the mast pulleys 32. Since the counterweight 'assembly 38 ismounted on the intermediate carriage it will obviously move with theintermediate carriage by that amount. Since it is connected at 40 to thecarriage cable 37 which is moving relative to the intermediate carriage33, the counterweight assembly 38 is also caused to move upwardlyrelative to the intermediate carriage. The total of these two movementsof the counterweight assembly results in its moving a distance twicethat of the spot filmer 17. Since the amount of movement is twice thatof the spot filmer 17 the amount of weight needed to counterbalance thespot filmer is essentially one-half that of the spot filmer, friction inthe system causing it to be slightly different than one-half.

Referring now to FIGS. 2-5, the components there corresponding to thosedescribed in connection with the schematic showing of FIGS. 6 and 7 areidentified by like numerals. In the actual construction, there are fourendless cables, two mast cables 31 mounted on opposite sides of themast, and two carriage cables 37 carried by the intermediate carriage33.

The four mast pulleys 32 are journaled on flanges 45 which are fixed tothe mast 18. The pulleys 32 are journaled for rotation about axes whichparallel the transverse dimension of the table. To insure against anypossible slippage each mast cable 31 is actually made of two portions ofequal length. One end of each of the portions is anchored at 34 on theintermediate carriage 33. The other ends, not shown, are similarlyanchored on the spot filmer after being reeved about a snub baridentified in FIGS. 4 and 5 by the numeral 30 to designate theconnection of the cable 31 to the spot filmer carriage.

The intermediate carriage 33 includes a vertical plate portion 47 whichforms its back. The intermediatecarriage has a base portion 48 which ishorizontally disposed and which may be formed by bending a plate toprovide both the back and the base portions. The base portion 48 has anopening at 49 through which part of the counterweight assembly mayproject when in the lowered or storage positions. The base portion 48also carries the pair of bumpers 50 of rubber or similar material, onlyone of which is visible in FIG. 4. These bumpers 50 engage thecounterweight assenbly 38 when it is in its fully lowered position asshown in FIG. 5.

The intermediate carriage 33 has side portions 52, 53, FIG. 3, whichproject forwardly from the back portion 47 and are perpendicular to it.The side portions 52, 53 carry mounting flanges 54, 55 which projecthorizontally outwardly. The mounting flanges 54, 55 carry two pairs ofcarriage rollers 56, 57. The carriage rollers 56, 57 engage mast tracks59, 60 carried on the sides of the mast. The engagement of the rollers56, 57 in the tracks 59, 60 provides guiding movement.

In FIGS. 2-5 counterweight carriage 61 of the counterweight assembly 38is shown but the counterweight themselves are omitted for clarity ofillustration. The counterweight carriage 61 includes a horizontallydisposed platform portion 62 upon which counterweights may be mountedTheplatform 62 extends on either side of a vertical support portion63 ofthe counterweight carriage. The counterweight carriage 61 includes ahorizontal pair of flanges 6,4 tolwhich the end- Iess cables 37 areconnected at 40. The counterweight carriage rollers 39 are journaledonthe vertical support plate portion 63 and positioned to engage guidetracks 65, 66 which are projvided'on the side portions of theintermediate carriage 33. l

A pair of cable anchor brackets 67 are provided on opposite sides offront wall 68 of the mast 18. The brackets 67 have bolts extendingtherethrough to provide the anchor 36 for the endless cable 37. Toassist in effecting this anchoring of the cable 37, snubs.69 areprovided and secured near the tops of the bracket 67.

Spot Filmer Parking the spot filmer tracks 22 is visible in each of theviews and portions of the mast tracks 19, 20 are shown.

A spot fllmer position latch 70 is provided. The position latch ispivotally mounted at 71 on the spot filmer carriage 21. The positionlatch 70 selectively engages either a park position'notch 72 or anoperating position notch 73. The notches 72, 73 are formed in the spotfilmer guide track 22.,A latch groove 74 extends from one notch to theothe r so that the upper portion of the position latch 70 remainspartially disposed within the spot filmer track22 at all times in amanner which will be described in moredetail.

The parked position notch 72 has its forward surface defined by areciprocally movable latch bumper 76. The latch bumper 76 can moveforwardly, to the-right in FIGS. 8-10, against the resilient compressionof a cushion 77 carried within the track 22. Thus, when the spot filmerreaches the park position shown in FIG. 8 and the latch 70 engages thebumper 76 to stop the parking movement,-the stopping action is cushionedby the sliding movement of the latch bumper 76 acting against the latchcushion 77. Similarly, when the spot filmer is moved rectil'inearlyforwardto its operating position, sliding movement of a latch bumper 78against another Iatch'cushion 79 cushions the stopping action of thespot filmer as it reaches its forward operation position. i

When one wishes to move the spot filmer from the park position shown inFIG. 8 forwardly to the operating position of FIG. 10, a latch releasebutton 80 is depressed. As the latch button 80 is depressed a button pin81 compresses a button spring 82. As soon as the button is released thespring 82 acting against the pin 81 will return the button to theposition shown in FIG. 8.

The pressing of the latch button 80 causes a latch pivot link 83 topivot about its mounting 84 on the spot filmer carriage 21. A latchactuating link 85 is pivotally connected to the latch 70 and to thepivot link 83. The pivoting of the latch pivot link 83 shifts the latchactuating link 85 rearwardly causing the position latch 70 to pivotabout its pivot 71. This pivoting of the latch 70 lowers the latchsufficiently to permit the spot filmer to be pulled forwardly while thetop portion of the latch 70 is in the latch groove 74. I

The spot filmer 17 must be at the top of its travel before it can passover the tracks 20, 20a to the parked position. The spot filmer ismaintained in its upward position when it is parked. The maintenance ofth spot filmer in this upward position is provided by a verticalposition link 87. The vertical position link 87 overlies and engages thetop of track 20 when the spot filmer carriage 21 is in the park positionand substantially at the top of its travel.

A vertical position control link 88 is connected to the verticalposition link 87 and to the position latch 70 by lost motion connections89, 90 respectively. At the time when the spot filmer is being broughtforwardly from its park position of FIG. 8 to its operating position ofFIG. 10, the weight of the spot filmer holds the vertical position link87 in engagement with the top of the mast track 20. When this engagementexists, depression of the release button 80 and the resultant movementof the position latch 70 has no effect on this vertical holding actionof the vertical link 87. This is accomplished by the lost motionconnections 89, 90 which permit this movement of the latch 70 while thevertical link 87 remains stationary.

Once the spot filmer has reached the forward position shown in FIG. 10,a latch spring 92 will pivot the latch 70 about its pivot 71, causingthe top portion of the latch to move into and engage the notch 73. Thisengagement of the link 70 with the notch prevents rearward movement ofthe spot filmer until such time as the spot filmer is raised fully andthe button 80 is depressed. Again, because of the lost motionconnections 89, 90, this latch action can occur without the verticalposition link 87 leaving its position engaging the top link 20. Slightupward manipulation of the spot filmer will lift the vertical link 87off the top of the track 20.

A limit switch 95 is provided. The limit switch is a normally openswitch which is depressed by the vertical link 87 when it is forward ofthe track 20. Depressing 'of the limit switch 95 closes it enabling anX-ray exposure to be taken. Whenever the link 87 is in its position overthe track 20, the limit switch 95 is open serving as a safety precautionby preventing an X-ray exposure from being taken.

The shifting of thespot filmer from its operating position of FIG. tothe park position of FIG. 8 is the reverse of the operation thus fardescribed. The spot filmer is first elevated to the top of its travel.The latch release button 80 is depressed, shifting the vertical positionlink 87 over the track and the latch 72 out of the notch 73. Once thelatch 70 has been pivoted sufficiently to come out of the notch 73,rearward pressure on the spot filmer will shift it rearwardly until thelatch 70 engages the latch bumper 76 and pivots into engagement with thepark notch 72.

The rearward shifting of the spot filmer and the natural action as theparking is acheived, shifts the carriage downwardly enough that thevertical link 87 moves into engagement with the top of the track 20 andwill remain there once the button is released until action is taken toshift the spot filmer out of the park position. Moreover, even if thelatch 87 should be brought forward by the action of the spring 93 oncethe spot film er is in its parked position, substantially no downwardmovement is obtainable because the spot filmer is over the top of themast 18 and will rest against it.

Another outstanding feature of the latch release structure is that itprevents movement of the spot filmer rearwardly from its operatingposition unless the spot filmer has been moved to the top of its travel.To accomplish this, the vertical link 87 is positioned such that it willstrike the front of the track 20 if the button is depressed at a timewhen the spot filmer is not raised to a point when it can pivot over thetop of the track 20. The lost motion connections 89,90, the depth of thegroove 74 and the size of the latch 70 are such that the latch 70 cannotbe pivoted about its pivot 71 a sufficient amount to come out of thenotch 73 until the vertical link 87 is able to move over the top of thetrack 20. Thus, one cannot accidentally shift the spot filmer out of itsoperating position until the spot filmer carriage has been movedsubstantially to the top of its permissible travel.

The spot filmer of this invention is preferably used in conjunction withautomatic X-ray shutter control which will be described in anapplication to be filed by E. A. Norgren. A portion of that automaticshutter control is shown in FIGS. 3 and 5.

A shutter-control bracket is mounted in the last 18. The shutter-controlbracket 100 supports a guide rod 101. A position control member 102 isprovided which has upper and lower apertured flanges 103. The guide rod101 projects through the apertures in the flanges 103.

The position-control member 102 is, in the embodiment shown, connectedby a connecting portion 104 to the intermediate carriage 33. As theintermediate carriage 33 moves up and down, the position-control membermoves up and down with it. The positioncontrol member is guided along arectilinear path by the guide rod 101.

The position-control member 102 carries a pair of rollers 105. Arheostat control shaft 106 is journaled on the shutter-control bracket100 and engaged by the rollers 105. The control shaft 106 is rectangularincrosssection and of a longitudinally twisted or spiral configuration.As the position-control member 102 moves up and down with theintermediate carriage 33, the control rollers 105 engage the surface ofthe control shaft 106, causing it to rotate.

Rotation of the control shaft 106 causes rotation of the rotatablecontactors of a pair of pots or variable rheostats 107. The rheostatsare connected into the shutter control circuit so that rotation of themcauses automatic compensation in that circuit for the position ofthe-spot filmer.

Although the invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thearrangement of parts may be resorted to without departing from thespirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. An X-ray apparatus, comprising:

a. a table having a tiltable body;

b. a tower movably carried on said body;

c. a mast forming part of said tower and supporting a mechanism forcontributing to the production of an X-ray image for movement along amechanism path toward and away from said body between mechanism extendedand mechanism storage positions, said mechanism extended position beingnearer said table body than said mechanism storage position;

(1. counterweight structure forming part of said tower and being movablealong a structure path which is substantially parallel to said imagingpath between structure extended and structure storage'positions;

e. coupling means coupling said mechanism and said structure for movingsaid structure along said structure path a certain distance in responseto movement of said mechanism along said mechanism path a lesserdistance, said couplingmeans.

being operable to position said structure in said structure extendedposition when said mechanism is in said mechanism extended position, andbeing operative to position said structure in said structure storageposition when said mechanism is in said mechanism storage position;

f. said mechanism being movable, when in said mechanism storageposition, along said parking path which intersects said structure pathto position said mechanism in a parked position; said coupling meansbeing operative to move said structure across said parking path whensaid mechanism moves from said mechanism storage position to saidmechanism extended position; and,

h. said coupling means being operative to prevent collision between saidmechanism and said structure when said mechanism is moved along saidparking path.

2. The apparatus of claim 1 additionally including means prohibiting themovement of said mechanism in directions toward and away from saidstructure path except when said mechanism is in said mechanism storageposition.

3. An X-ray apparatus comprising:

a. an X-ray table having a top tiltable from the horizontal position toanother position and return;

b. a column mounted in the table for movement relative to the table top;

c. said column including a vertical mast;

d. an imaging carriage device mounted on the mast forreciprocationtoward and awayfrom the table e. an imaging device mounted on thecarriage device and reciprocal relative to the carriage device from anoperating position forward of the mast to a park position above themast;

f. an intermediate carriage journaled within the mast for verticalmovement relative thereto;

g. a counterweight assembly journaled on the intermediate carriage andmovable relative thereto;

h. a pulley and cable system interconnecting the device and theintermediate carriage and the intermediate carriage and thecounterweight assembly respectively;

i. said counterweight assembly having a top position projecting abovesaid mast and a lower park position within the mast; and, i

j. said devices being coupled to a latching means maintainingsaid'irnage device in its front operating position at all times otherthan when the carriage device is raised to a height where the imagingde-.

b. a latching mechanism carried by the other of the I devices andincluding a latch 'pivotally mounted thereon; c. said truck includingpark and operating position notches; i I d. said latch being selectivelyengageable with the notches one at a time; 7 latch release meansconnected to the latch and actuatable tp pivot the latchout ofengagement with a selected one of said notches; and, I f. verticalposition maintenance means carried by a selected one of the mast and thedevices, said maintenance means being selectively positionable between afirst of said devices and said mast to maintain said devices in anelevated position when the imaging device is in its park position and toprevent movement of the imaging device from its operating position toits park position until' the imaging carriage is adequately elevated forparking movement.

5. In an X-ray apparatus having atable having a pedestal, a bodytiltably mounted on the pedestal for tilting from a horizontal to avertical position, and a tower asembly movably carried by the body andincluding a mast supporting said imaging device for movement toward andaway from the table body, the improvement weight assembly comprises acounterweight carriage journaled on the intermediate carriage forvertical reciprocal movement relative thereto and counterweights mountedon said counterweight carriage.

7. The apparatus of clain 6 wherein the counterweight coupling meanscomprises pulley and cable systems respectively connecting theintermediate carriage to the imaging device and the counterweightassembly to the intermediate carriage and arranged such that thecounterweight assembly moves substantially twice said given distance onmovement of the imaging device.

8. The device of claim 5 wherein the intermediate carriage and thecounterweight assembly have extended positions wherein both'extend abovethe top of counterweight coupling meanscoupling the imag- Eli the mastand wherein said intermediate carriage and counterweight assembly aremaintained in said extended position by the coupling means when saidimaging device is in its lowermost position.

5 lln an Xray apparatus including an imaging device carriage mounted ona mast and movable reciprocally on mast tracks and an imaging devicehaving tracks mounted on the carriage for reciprocal movement therealongin a path generally normal to the path of carriage movement on saidmast, an improved latching mechanism comprising:

a. one of said image device tracks including spaced park and operatingposition notches;

b. a latch pivotally mounted on said carriage and selectively engageablewith said notches one at a time;

c. manually actuatable linkage connected to said latch for selectivelypivoting said latch out of engagement with each of said notches;

d. resilient means biasing said latch into said notches selectively andone at a time whenever said linkage is released and the latch is alignedwith one of the notches;

e. a vertical position maintenance link pivotally mounted on saidcarriage;

f. a lost motion connection between said vertical link and said latch;and,

g. said vertical link being positioned such that when the carriage issubstantially in its uppermost position actuation of the manuallyactuatable linkage will pivot the vertical link over the top of one ofsaid mast tracks and the latch will come out of the operating positionnotch but when the imaging device is in an operating position and thecarriage is not sufticiently elevated, the link will strike the masttrack and prevent disengagement of the latch with the operating positionnotch.

10. The apparatus of claim 9 wherein a second resilient means biasessaid vertical link from its park position over said one mast track.

11. In an X-ray apparatus including a table having a pedestal, a bodytiltably mounted on the pedestal for tilting from a horizontal to avertical position, and a tower assembly movably carried by the body, thetower assembly including a mast supporting an imaging device formovement toward and away from the table body, the improvementcomprising:

a. a counterweight assembly forming part of the tower assembly, thecounterweight assembly being mounted on the mast and movable relativethereto;

counterweight coupling means coupling the imaging device to thecounterweight assembl y such that on movement of the imaging device a"given distance the counterweight assembly will move a greater distancethan the imaging device thereby providing a mechanical advantage;

c. parking means coupling the imaging device to the remainder of thetower assembly and permitting selective rectilinear movement of theimaging device rearwardly from an operating position forward of the mastto a park position over the top of said counterweight assembly;

d. said tower assembly including an imaging device carriage reciprocallymounted on the mast and carrying said image device;

e. latch means to lock the imaging device selectively in the operatingposition or in the park position; and,

f. the latch means including a means to maintain the carriage in itsfully-elevated position and preventing the movement of the imagingdevice from the position of the park position whenever the imagingdevice carriage is below its park position.

12. in an X-ray apparatus including a carriage device reciprocallymounted on a mast for movement toward and away from an X-ray table, andan imaging device reciprocally mounted on the carriage device formovement along a rectilinear path paralleling the table top from anoperating position to a park position, a latching structure comprising:

a. a track on one of the devices and journaled for reciprocal movementon the other of the devices;

b. a latching mechanism carried by the other of the devices andincluding a latch pivotally mounted thereon;

c. said track including park and operating position notches;

d. said latch being selectively engageable with said notches one at atime;

c. latch release means connected to the latch and actuatable to pivotthe latch out of engagement with a selected one of said notches; and,

f. vertical position maintenance means carried by a selected one of themast and the devices, said maintenance means being selectivelypositionable between a first of said devices and said mast to maintainsaid devices in an elevated position when the imaging device is in itspark position and to prevent movement of the imaging device from itsoperating position to its park position until the imaging carriage isadequately elevated for parking movement.

13. The apparatus of claim 12 wherein the position maintenance iscarried by one of the devices and engageable with a track on the mast.

14. The apparatus of claim 12 wherein there is a lost motion connectionbetween the latch and the position maintenance means.

15. In an X-ray apparatus including a table having a pedestal, a bodytiltably mounted on the pedestal for tilting from a horizontal toavertical position, and a tower assembly movably carried by the body,the improvement comprising:

a. said tower assembly including a mast subassembly supporting animaging device for movement longi tudinal of the tower assembly towardand away from the table body;

b. a counterweight subassembly forming part of the tower assembly, thecounterweight subassembly being carried by the mast subassembly andmovable relative thereto;

c. counterweight coupling means coupling the imaging device to thecounterweight subassembly such that on movement of the imaging device agiven distance the counterweight subassembly will move a certaindistance;

d. said subassemblies having a storage position andv an extendedposition, the combined dimension of the subassemblies longitudinally ofthe tower being greater when in the extended position than when in thestorage position; and,

e. parking means coupling the imaging device to the remainder of thetower assembly and permitting selective rectilinear movement oftheimaging device rearwardly from an operating position forward of themast subassembly to a park position over the subassemblies when they arein the storage position.

16. The apparatus of claim 15 wherein the counterweight subassembly istelescopically carried by the mast subassembly.

17. The apparatus of claim 16 wherein a counterweight subassembly isfully within the mast subassembly within said storage position andprojects outwardly of the mast subassembly when in said extendedposition.

18. The apparatus of claim 15 wherein said certain distance is greaterthan said given distance thereby providing a mechanical advantage.

19. The apparatus of claim 15 wherein the image device is movable to itspark position only when it is sub- 21. The apparatus of claim 19 whereina means prevents movement of the imaging device toward the table bodywhen the imaging device is in its park position.

22. The apparatus of claim 15 wherein the counterweight subassemblyincludes a counterweight carriage and an intermediate carriage.

23. The apparatus of claim 22 wherein the counterweight carriage and theintermediate carriage are mov- 'able relative to one another andrelative to the mast subassembly.

24. The apparatus of claim 23 wherein the counterweight carriageprojects from the intermediate carriage and both carriages project fromthe mast subassembly when in said extended position.

25. In an X-ray apparatus including a table having a pedestal, a bodytiltably mounted on the pedestal for tilting from a horizontal to avertical position, and a tower assembly movably carried by the body, thetower assembly including a mast supporting an imaging device formovement toward and away from the table body, the improvementcomprising:

a. a counterweight assembly forming part of the tower assembly, thecounterweight assembly being mounted on the mast and movable relativethereto;

b. counterweight coupling means coupling the imaging device to thecounterweight assembly such that on movement of the imaging device agiven distance the counterweight assembly will move a greater distancethan the imaging device thereby providing a mechanical advantage;

c. parking means coupling the imaging device to the remainder of thetower assembly and permitting selective rectilinear movement of theimaging device rearwardly from an operating position forward of the mastto a park position over the top of said counterweight assembly;

d. the counterweight assembly being movable to an extended positionprojecting above the top of the mast; and,

e. the imaging device being in its lowermost position when the couplingmeans maintains the counterweight assembly in its extended position.

26. An X-ray apparatus, comprising:

a. a table having a body tiltable between horizontal and verticalpositions;

b. a tower movably carried on said body;

, c. a counterweight subassembly forming part of said tower and beingmovable longitudinally of said tower along a first path betweencounterweight extended and counterweight storage positions;

(1. a mast subassembly forming a part of said tower and supporting animaging device for movement longitudinally of said tower along a secondpath substantially parallel to said first path between device extendedand device storage positions, said device extended position being nearersaid table body than said device storage position;

e. coupling means coupling said imaging device and said counterweightsubassembly for moving said counterweight assembly along said first patha certain distance in response to movement of said imaging device alongsaid second path a lesser distion said counterweight subassembly in saidcounterweight extended position when said imaging device is in saiddevice extended position, and being operative to position saidcounterweight subassembly in said counterweight storage position whensaid imaging device is in said device storage position; said imagingdevice being movable, when in said device storage position, along aparking path which intersects said first path to position said imagingdevice in a parked position along said first path; said counterweightstorage position being sufficiently removed from said parked position toprevent collision between saidimaging device and said counterweightsubassembly when said imaging device is moved along saidrparking path;and,

h. said coupling means being operative to move said counterweightsubassembly across said parking path when said imaging device moves fromsaid device storage position to said device extended position.

27. The apparatus of claim 26 and additionally including parking meansprohibiting the movement of said imaging device along said parking pathexcept when said imaging device is in said device storage position. i

28. The apparatus of claim 27 wherein said parking means includes anacutator button which is operable when said imaging device is in saiddevice storage position to permit the movement of said imaging devicealong said parking path, and control means for preventing the operationof said actuator button when said imaging device is removed from saiddevice storage position.

29. The apparatus of claim 26 wherein said counterweight subassembly ispositioned across said parking path when said imaging device is in saiddevice extended position.

30. The apparatus of claim 29 wherein said coupling means includes cablemeans interconnecting said counterweight subassembly annd said imagingdevice for moving said counterweight subassembly acrosssaid first pathin a direction opposite to the movement of said imaging device alongsaid second path in response to movement of said imaging device alongsaid second path, whereby said counterweight subassembly moves towardsaid table body from said counterweight exsembly along said first paththrough approximately twice a given distance in response to movement ofsaid imaging device along said second path through said given distance.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. 3,916 ,203

DATED October 28, 1975 |NV ENTOR(S) Edwin A. Norgren It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below: Under "References Cited""Keipaur" should be Kizaur Col. 2, line 57, "coutnerweights" should becounterweights Col. 4, line 5, "embodiment" should be embodied Col. 4,line 37, "any" should be and Col. 4, line 54 "mechanism" should bemechanics Col. 4, line 56, "Phantom" should be phantom Col. 6, line 1,"assenbly" should be assembly Col. 7, line 17, before spot", "th" shouldbe the Col. 7, line 46, after "top" insert of Col. 8, line 2, "acheived"should be achieved Col. 8, line 34 "last" should be mast Claim 1, 1lf.,line 2, "said" should be a Claim 3, 1th., lines land 2, "device" shouldbe devices 1Ij. line 2, "front" should be forward Q Claim 4, 1Ia. line1, "journalled" should be journaled 1[e., line 2, "tp" should be toClaim 5, line 4, "asembly" should be assembly Claim 7 line 1, "clain"should be claim Claim ll, line ll, before "counterweight, "insert b.

1If., line 4, before "position", lst occur. insert Q operating fitf.line 4, delete "of" substitute to Claim 13, line 2 after "maintenance"insert means Claim 26, 1[f., line 4, before "said" insert g. Claim 27,line 1, after "26" delete "and" Claim 30, line 3, after "subassembly"delete "annd" and sub- Q stitute and Signed and Sealed this Third Day fFebruary 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner uj'larenrsand Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OFCORRECTION PATENT N0. 3,916,203

DATED October 28, 1975 INV ENTOR(S) ZEdWin A. Norgren It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Under "References Cited" "Keipaur" should be Kizaur Col. 2, line 57,"coutnerweights" should be counterweights Col. 4, line 5 "embodiment"should be embodied Col. 4, line 37, "any" should be and Col. 4, line 54"mechanism" should be mechanics T Col. 4, line 56 "Phantom" should bephantom Col. 6, line 1, "assenbly" should be assembly T l Col. 7, line17, before "spot" "th" should be the Col. 7, line 46, after "top" insertof Col. 8, line 2, "acheived" should be achieved Col. 8, line 34, "last"should be mast Claim 1, Hf. line 2 "said" should be a Claim 3, 11h.lines 1 and 2 "device" should be devices A 1Ij line 2 "front" should beforward Claim 4, 1Ia. line 1, "journalled" should be journaled 1le. line2 "tp" should be to 7 Claim 5, line 4, "asembly" should be assemblyClaim 7 line 1, clain" should be claim 7 Claim ll, line ll, before"counterweight,"insert b. 1If. line 4 before "position" lst occur.insert operating A A 1If. line 4 delete "of" substitute to I Claim 13,line 2, after "maintenance" insert means Claim 26, 1Tf. line 4 before"said" insert g.

Claim 27 line 1, after "26" delete "and" Claim 30, line 3, after"subassembly" delete "annd" and substitute and Signed and Scalcdthisthird Day of Februanv1976 [SEAL] 1 A Attest:

RUTH c. MASON CQMARSHALL DANN Arresting Officer Cummissioner uj'Patentsand Trademarks

1. An X-ray apparatus, comprising: a. a table having a tiltable body; b.a tower movably carried on said body; c. a mast forming part of saidtower and supporting a mechanism for contributing to the production ofan X-ray image for movement along a mechanism path toward and away fromsaid body between mechanism extended and mechanism storage positions,said mechanism extended position being nearer said table body than saidmechanism storage position; d. counterweight structure forming part ofsaid tower and being movable along a structure path which issubstantially parallel to said imaging path between structure extendedand structure storage positions; e. coupling means coupling saidmechanism and said structure for moving said structure along saidstructure path a certain distance in response to movement of saidmechanism along said mechanism path a lesser distance, said couplingmeans being operable to position said structure in said structureextended position when said mechanism is in said mechanism extendedposition, and being operative to position said structure in saidstructure storage position when said mechanism is in said mechanismstorage position; f. said mechanism being movable, when in saidmechanism storage position, along a parking path which intersects saidstructure path to position said mechanism in a parked position; g. saidcoupling means being operative to move said structure across saidparking path when said mechanism moves from said mechanism storageposition to said mechanism extended position; and, h. said couplingmeans being operative to prevent collision between said mechanism andsaid structure when said mechanism is moved along said parking path. 2.The apparatus of claim 1 additionally including means prohibiting themovement of said mechanism in directions toward and away from saidstructure path except when said mechanism is in said mechanism storageposition.
 3. An X-ray apparatus comprising: a. an X-ray table having atop tiltable from the horizontal position to another position andreturn; b. a column mounted in the table for movement relative to thetable top; c. said column including a vertical mast; d. an imagingcarriage device mounted on the mast for reciprocation toward and awayfrom the table top; e. an imaging device mounted on the carriage deviceand reciprocal relative to the carriage device from an operatingposition forward of the mast to a park position above the mast; f. anintermediate carriage journaled within the mast for vertical movementrelative thereto; g. a counterweight assembly journaled on theintermediate carriage and movable relative thereto; h. a pulley andcable system interconnecting the devices and the intermediate carriageand the intermediate carriage and the counterweight assemblyrespectively; i. said counterweight assembly having a top positionprojecting above said mast and a lower park position within the mast;and, j. said devices being coupled to a latching means maintaining saidimage device in its forward operating position at all times other thanwhen the carriage device is raised to a height where the imaging devicecan pass over the mast assembly when shifted rearwardly and said latchmeans is released.
 4. The apparatus of claim 3 wherein said latch meanscomprises: a. a track on one of the devices and journaled for reciprocalmovement on the other of the devices; b. a latching mechanism carried bythe other of the devices and including a latch pivotally mountedthereon; c. said truck including park and operating position notches; d.said latch being selectively engageable with the notChes one at a time;e. latch release means connected to the latch and actuatable to pivotthe latch out of engagement with a selected one of said notches; and, f.vertical position maintenance means carried by a selected one of themast and the devices, said maintenance means being selectivelypositionable between a first of said devices and said mast to maintainsaid devices in an elevated position when the imaging device is in itspark position and to prevent movement of the imaging device from itsoperating position to its park position until the imaging carriage isadequately elevated for parking movement.
 5. In an X-ray apparatushaving a table having a pedestal, a body tiltably mounted on thepedestal for tilting from a horizontal to a vertical position, and atower assembly movably carried by the body and including a mastsupporting said imaging device for movement toward and away from thetable body, the improvement comprising: a. an intermediate carriagemovably carried by the mast; b. a counterweight assembly movably carriedby the mast; and, c. counterweight coupling means coupling the imagingdevice, the counterweight assembly and the intermeidate carriagetogether such that on movement of the imaging device a given distancethe intermediate carriage will move a certain distance in a directionopposite the imaging device and the counterweight assembly will move agreater distance than the imaging device thereby providing a mechanicaladvantage to the counterweight.
 6. The apparatus of claim 5 wherein thecounterweight assembly comprises a counterweight carriage journaled onthe intermediate carriage for vertical reciprocal movement relativethereto and counterweights mounted on said counterweight carriage. 7.The apparatus of claim 6 wherein the counterweight coupling meanscomprises pulley and cable systems respectively connecting theintermediate carriage to the imaging device and the counterweightassembly to the intermediate carriage and arranged such that thecounterweight assembly moves substantially twice said given distance onmovement of the imaging device.
 8. The device of claim 5 wherein theintermediate carriage and the counterweight assembly have extendedpositions wherein both extend above the top of the mast and wherein saidintermediate carriage and counterweight assembly are maintained in saidextended position by the coupling means when said imaging device is inits lowermost position.
 9. In an X-ray apparatus including an imagingdevice carriage mounted on a mast and movable reciprocally on masttracks and an imaging device having tracks mounted on the carriage forreciprocal movement therealong in a path generally normal to the path ofcarriage movement on said mast, an improved latching mechanismcomprising: a. one of said image device tracks including spaced park andoperating position notches; b. a latch pivotally mounted on saidcarriage and selectively engageable with said notches one at a time; c.manually actuatable linkage connected to said latch for selectivelypivoting said latch out of engagement with each of said notches; d.resilient means biasing said latch into said notches selectively and oneat a time whenever said linkage is released and the latch is alignedwith one of the notches; e. a vertical position maintenance linkpivotally mounted on said carriage; f. a lost motion connection betweensaid vertical link and said latch; and, g. said vertical link beingpositioned such that when the carriage is substantially in its uppermostposition actuation of the manually actuatable linkage will pivot thevertical link over the top of one of said mast tracks and the latch willcome out of the operating position notch but when the imaging device isin an operating position and the carriage is not sufficiently elevated,the link will strike the mast track and prevent disengagement of thelatch with the operating position notch.
 10. THe apparatus of claim 9wherein a second resilient means biases said vertical link from its parkposition over said one mast track.
 11. In an X-ray apparatus including atable having a pedestal, a body tiltably mounted on the pedestal fortilting from a horizontal to a vertical position, and a tower assemblymovably carried by the body, the tower assembly including a mastsupporting an imaging device for movement toward and away from the tablebody, the improvement comprising: a. a counterweight assembly formingpart of the tower assembly, the counterweight assembly being mounted onthe mast and movable relative thereto; b. counterweight coupling meanscoupling the imaging device to the counterweight assembly such that onmovement of the imaging device a given distance the counterweightassembly will move a greater distance than the imaging device therebyproviding a mechanical advantage; c. parking means coupling the imagingdevice to the remainder of the tower assembly and permitting selectiverectilinear movement of the imaging device rearwardly from an operatingposition forward of the mast to a park position over the top of saidcounterweight assembly; d. said tower assembly including an imagingdevice carriage reciprocally mounted on the mast and carrying said imagedevice; e. latch means to lock the imaging device selectively in theoperating position or in the park position; and, f. the latch meansincluding a means to maintain the carriage in its fully-elevatedposition and preventing the movement of the imaging device from theoperating position to the park position whenever the imaging devicecarriage is below its park position.
 12. In an X-ray apparatus includinga carriage device reciprocally mounted on a mast for movement toward andaway from an X-ray table, and an imaging device reciprocally mounted onthe carriage device for movement along a rectilinear path parallelingthe table top from an operating position to a park position, a latchingstructure comprising: a. a track on one of the devices and journaled forreciprocal movement on the other of the devices; b. a latching mechanismcarried by the other of the devices and including a latch pivotallymounted thereon; c. said track including park and operating positionnotches; d. said latch being selectively engageable with said notchesone at a time; e. latch release means connected to the latch andactuatable to pivot the latch out of engagement with a selected one ofsaid notches; and, f. vertical position maintenance means carried by aselected one of the mast and the devices, said maintenance means beingselectively positionable between a first of said devices and said mastto maintain said devices in an elevated position when the imaging deviceis in its park position and to prevent movement of the imaging devicefrom its operating position to its park position until the imagingcarriage is adequately elevated for parking movement.
 13. The apparatusof claim 12 wherein the position maintenance means is carried by one ofthe devices and engageable with a track on the mast.
 14. The apparatusof claim 12 wherein there is a lost motion connection between the latchand the position maintenance means.
 15. In an X-ray apparatus includinga table having a pedestal, a body tiltably mounted on the pedestal fortilting from a horizontal to a vertical position, and a tower assemblymovably carried by the body, the improvement comprising: a. said towerassembly including a mast subassembly supporting an imaging device formovement longitudinal of the tower assembly toward and away from thetable body; b. a counterweight subassembly forming part of the towerassembly, the counterweight subassembly being carried by the mastsubassembly and movable relative thereto; c. counterweight couplingmeans coupling the imaging device to the counterweight subassembly suchthat on movement of the imaging device a given Distance thecounterweight subassembly will move a certain distance; d. saidsubassemblies having a storage position and an extended position, thecombined dimension of the subassemblies longitudinally of the towerbeing greater when in the extended position than when in the storageposition; and, e. parking means coupling the imaging device to theremainder of the tower assembly and permitting selective rectilinearmovement of the imaging device rearwardly from an operating positionforward of the mast subassembly to a park position over thesubassemblies when they are in the storage position.
 16. The apparatusof claim 15 wherein the counterweight subassembly is telescopicallycarried by the mast subassembly.
 17. The apparatus of claim 16 wherein acounterweight subassembly is fully within the mast subassembly withinsaid storage position and projects outwardly of the mast subassemblywhen in said extended position.
 18. The apparatus of claim 15 whereinsaid certain distance is greater than said given distance therebyproviding a mechanical advantage.
 19. The apparatus of claim 15 whereinthe image device is movable to its park position only when it issubstantially at its maximum distance from the table body.
 20. Theapparatus of claim 19 wherein a latch means is interposed between theimaging device and the remainder of the tower assembly to prevent suchmovement to the park position until the image device is at such maximumposition.
 21. The apparatus of claim 19 wherein a means preventsmovement of the imaging device toward the table body when the imagingdevice is in its park position.
 22. The apparatus of claim 15 whereinthe counterweight subassembly includes a counterweight carriage and anintermediate carriage.
 23. The apparatus of claim 22 wherein thecounterweight carriage and the intermediate carriage are movablerelative to one another and relative to the mast subassembly.
 24. Theapparatus of claim 23 wherein the counterweight carriage projects fromthe intermediate carriage and both carriages project from the mastsubassembly when in said extended position.
 25. In an X-ray apparatusincluding a table having a pedestal, a body tiltably mounted on thepedestal for tilting from a horizontal to a vertical position, and atower assembly movably carried by the body, the tower assembly includinga mast supporting an imaging device for movement toward and away fromthe table body, the improvement comprising: a. a counterweight assemblyforming part of the tower assembly, the counterweight assembly beingmounted on the mast and movable relative thereto; b. counterweightcoupling means coupling the imaging device to the counterweight assemblysuch that on movement of the imaging device a given distance thecounterweight assembly will move a greater distance than the imagingdevice thereby providing a mechanical advantage; c. parking meanscoupling the imaging device to the remainder of the tower assembly andpermitting selective rectilinear movement of the imaging devicerearwardly from an operating position forward of the mast to a parkposition over the top of said counterweight assembly; d. thecounterweight assembly being movable to an extended position projectingabove the top of the mast; and, e. the imaging device being in itslowermost position when the coupling means maintains the counterweightassembly in its extended position.
 26. An X-ray apparatus, comprising:a. a table having a body tiltable between horizontal and verticalpositions; b. a tower movably carried on said body; c. a counterweightsubassembly forming part of said tower and being movable longitudinallyof said tower along a first path between counterweight extended andcounterweight storage positions; d. a mast subassembly forming a part ofsaid tower and supporting an imaging device for movement longitudinallyof said tower along a second path substantially parallel to said firstpath between device extended and device storage positions, said deviceextended position being nearer said table body than said device storageposition; e. coupling means coupling said imaging device and saidcounterweight subassembly for moving said counterweight assembly alongsaid first path a certain distance in response to movement of saidimaging device along said second path a lesser distance, said couplingmeans being operable to position said counterweight subassembly in saidcounterweight extended position when said imaging device is in saiddevice extended position, and being operative to position saidcounterweight subassembly in said counterweight storage position whensaid imaging device is in said device storage position; f. said imagingdevice being movable, when in said device storage position, along aparking path which intersects said first path to position said imagingdevice in a parked position along said first path; g. said counterweightstorage position being sufficiently removed from said parked position toprevent collision between said imaging device and said counterweightsubassembly when said imaging device is moved along said parking path;and, h. said coupling means being operative to move said counterweightsubassembly across said parking path when said imaging device moves fromsaid device storage position to said device extended position.
 27. Theapparatus of claim 26 additionally including parking means prohibitingthe movement of said imaging device along said parking path except whensaid imaging device is in said device storage position.
 28. Theapparatus of claim 27 wherein said parking means includes an acutatorbutton which is operable when said imaging device is in said devicestorage position to permit the movement of said imaging device alongsaid parking path, and control means for preventing the operation ofsaid actuator button when said imaging device is removed from saiddevice storage position.
 29. The apparatus of claim 26 wherein saidcounterweight subassembly is positioned across said parking path whensaid imaging device is in said device extended position.
 30. Theapparatus of claim 29 wherein said coupling means includes cable meansinterconnecting said counterweight subassembly and said imaging devicefor moving said counterweight subassembly along said first path in adirection opposite to the movement of said imaging device along saidsecond path in response to movement of said imaging device along saidsecond path, whereby said counterweight subassembly moves toward saidtable body from said counterweight extended position when said imagingdevice moves away from said table body from said device extendedposition.
 31. The apparatus of claim 30 wherein said coupling means isoperable to move said counterweight subassembly along said first paththrough approximately twice a given distance in response to movement ofsaid imaging device along said second path through said given distance.